Fast-acting fastener driving tools are commonplace in the building industry. Fasteners, such as nails or concrete or steel penetrating pins, are assembled in rows or strips that are adapted for use in the driving tools. The strips are typically essentially flat so that the fasteners are maintained in position parallel to each other.
One way to maintain the fasteners in position is described in U.S. Pat. No. 5,069,340, issued to Ernst et al., the disclosure of which is incorporated by reference. As explained in the reference, a plurality of collated fasteners, each having a shank and a head, is maintained in parallel relationship using a carrier molded from a polymeric material which can be polypropylene. The carrier includes a sleeve associated with each fastener.
A representative prior art fastener assembly is illustrated in FIG. 9, which shows a strip 10 of collated fasteners 12 (one of which is shown), held together by a carrier 30. Each fastener 12 is a drive pin, made from hardened steel, and is designed to be forcibly driven through a work piece, such as a galvanized steel channel or track, and into a substrate which can be made of concrete or steel. Each fastener 12 has an elongated shank 18 with a pointed end 20, and a head 22.
The polypropylene carrier 30 has a separate sleeve 32 for each fastener 12. Each sleeve 32 includes a lower annular portion 34 and an upper breakable portion 36 which is integral with the annular portion 34. Each sleeve 32 grips the shank 18 of the associated fastener 12, with the annular portion 34 nearer to the pointed end 20 of the shank 18, and with the breakable portion 36 nearer to the head 22.
In each sleeve 32, the breakable portion 36 has a pair of similar, laterally opposed, outwardly opening concave recesses 40 and 42. Between each pair of sleeves 32, an upper bridge 44 and lower bridge 46 are located, which hold the adjacent sleeves together. During operation, the entire fastener assembly 10 is placed in the magazine portion of the power driving tool. The power driving tool acts forcefully on the head 22 of the first fastener 12, driving it downward. The force causes the bridges 44 and 46 to break between the first and second sleeves 32, so that the first sleeve 32 separates from the carrier 30.
As the first fastener 12 is driven downward into an object, the upper breakable portion 36 of the first sleeve 32 ruptures at the recesses 40 and 42 and splits longitudinally into the two halves as the fastener 12 enters the object. However, the splitting usually does not extend to the lower annular portion 34 of the sleeve 32, and the annular portion 34 remains compressed between the head 22 of the fastener 12 and the object into which the fastener 12 is driven. Furthermore, the two halves of the upper (split) portion of the sleeve 32 usually remain integrally connected to the annular portion 34 and protrude outward from the object as "tails." This is more fully described in U.S. Pat. No. 5,069,340, the disclosure of which is incorporated herein by reference.
Because the surface into which the fasteners are driven is often hidden, the outward protrusion of "tails" does not present an aesthetic problem in many applications. However, there are some applications where aesthetics are important, or where an outer coating or object is to be placed directly on the substrate. These latter applications generate a need or desire for fastener assemblies which do not generate outwardly protruding tails, or other residual fastener sleeve parts.